The Prime Minister's Official Spokesman said: "I think people up and down the country will understand and be moved by the grave illness from which Ashya is suffering. The priority must be that he receives the most appropriate care.

"Parental instincts are to do the very best for your child. The priority here is the little boys health. It is also understandable that the relevent authorities take an interest in cases."

Naveed King, Ashya’s second eldest brother, posted a video of himself on the internet on support of his parents ahead of their court case on Monday.

In a new video posted late Sunday he said the family had travelled to Spain with all the necessary medical equipment for Ashya and had even bought him a new £1,600 wheelchair.

Holding up bags of the special food which was administered to Ashya on the journey from the UK to Spain he explained that it was exactly the same as he had received in hospital.

"This is the same food, we bought it online and we had a box load," explained Naveed on the video uploaded onto youTube.

He then held up a charger for use in a car. "We had this power cord which was what the feeding line was on in the car, so he was not starving along the way.

Naveed said his father was constantly researching " to find information that could help Ashya which the doctors ignored".

"They did not want to hear anything about his research as they did not believe any of the information that was being given, saying that the internet could not be trusted," he said.

The Kings’ eldest son Danny had earlier defended his father Brett, due to appear in court on Monday at an extradition hearing with wife Naghmeh.

Speaking to leading local Spanish paper Sur as he left the hostel where they were arrested with the five siblings he is now looking after, the 22-year-old said: “My parents are not kidnappers.

“They just want the best for our brother Ashya with an alternative type of treatment to the one he was receiving at the hospital in England.

“It might seem like madness what we’ve done coming here by car from Great Britain but it’s got nothing to do with the fact we’re Jehovah’s Witnesses.

“When they operated on him two months ago, we agreed to them doing blood transfusions but thankfully it wasn’t necessary.

“We want to see our brother in hospital, we just want what’s best for him. Money is not important, health is the most important thing.

“My parents are ready to sell their house if they have so they’ve got enough money to save Ashya’s life.”

Ashya's grandmother said it was an "absolute disgrace" that her son and daughter-in-law had been taken away in handcuffs, accused of child neglect.

Mr King's mother, Patricia King, told BBC Breakfast: "They (the authorities) are the ones who are cruel because they have taken poor little Ashya who is dying of a brain tumour and they won't let the parents, my son and daughter-in-law, they won't let them see him at all. It's terrible, it is so cruel it is unbelievable.

She added: "To try and make out that he has been neglected well. Why haven't we got any human rights? They keep on, the EU, about human rights. Where are our human rights? We have got none."